1. Field of the Invention
This invention relates to a slider member for an optical recording head adapted for recording and/or reproducing signals on or from a recording medium, such as an optical disc, a method for producing the slider member, and a recording and/or reproducing apparatus for recording and/or reproducing signals on or from a recording medium by an optical head employing such optical head.
2. Description of Related Art
An optical disc for recording and/or reproducing signals by illuminating light on a signal recording surface, such as a magneto-optical disc or a phase-change disc, is now in widespread use. In such optical disc, attempts are now being made in increasing the recording density by reducing the light spot diameter on the signal recording surface of the optical disc with a view to increasing the volume of the recordable information to the maximum extent possible.
In keeping up with the increasing recording density for the optical disc, attempts are also being made for reducing the spot diameter of the light illuminated on the signal recording surface of the optical disc to increase the recording density in an optical pickup configured for recording and/or reproducing signals on or from an optical disc.
Recently, it has been proposed to construct a slider member for an optical head carrying an optical lens, by utilizing the technique of the floating head slider in e.g., a hard disc device, and to collect and illuminate light on the signal recording surface of the optical disc by the optical lens loaded on the slider member to record and/or reproduce the signals, as the slider member is floated a pre-set amount above the signal recording surface.
If such slider member for the optical head is used in the optical disc device, the distance between the optical lens and the signal recording surface of the optical disc can be reduced significantly as compared to that when the light is illuminated on the signal recording surface of the optical disc from an optical head not provided with the slider member for the optical head. This enables the high NA lens to be used to reduce the spot diameter of the light illuminated on the signal recording surface of the optical disc.
If, in this optical disc device, a magneto-optical disc is to be used, magnetic field generating means needs to be provided for applying a magnetic field to the magneto-optical disc.
This magnetic field generating means may be provided separately from the above-mentioned slider member for the optical head. However, for reducing the size or simplifying the structure of the optical disc device, this slider member for the optical head is desirably provided as one with the slider member for the optical head. In such case, the magnetic field generating means is formed e.g., by a thin film coil embedded in a surface of the slider member facing the magneto-optical disc, and is mounted for encircling the focal point of the laser beam.
FIG. 1 shows a typical structure of the slider for the optical head. A slider for the optical head 100, shown in FIG. 1, includes a slider member 102, adapted for floating and running over a magneto-optical disc 101 during signal recording and/or reproduction on or from the magneto-optical disc 101, and an optical lens 103 joined to the slider member 102. An optical fiber 104 and a polarizing mirror 105 are built into the slider member 102. A light beam L, guided by the optical fiber 104, is incident on and collected by the optical lens 103 through the polarizing mirror 105. The laser beam L, collected by the optical lens 103, is illuminated on a signal recording layer 101a of the magneto-optical disc 101.
This slider member 102 includes a thin-film coil 106 for applying a magnetic field across the magneto-optical disc 101 during recording and a terminal 107 electrically connected to this thin-film coil 106. The thin-film coil 106 is formed on the surface of the slider member 102 facing the magneto-optical disc 101 by being coiled around the optical lens 103. On the other hand, the terminal 107 is formed by an electrically conductive material being charged in a through-hole bored in the slider member 102 along its thickness to a position of an abutment with the thin-film coil 106.
The slider member 102 is mounted on the distal end of a supporting arm 109 provided in the optical disc device to scan the magneto-optical disc 101 as the disc is run in rotation. The slider member 102 is also moved along the radius of the magneto-optical disc 101 as the supporting arm 109 is rotated.
A slider for the optical head 100, described above, is floated over the magneto-optical disc 101 a pre-set amount under an air stream produced on rotation of the magneto-optical disc 101. The slider for the optical head 100, thus floated, illuminates a laser beam L, collected by the optical lens 103 loaded on the slider member 102, on the signal recording layer 101a of the magneto-optical disc 101. Signal recording and/or reproduction on or from the magneto-optical disc 101 is achieved by illuminating the laser beam L on the signal recording layer 101a. 
During recording, the thin-film coil 106 generates a magnetic field of a pre-set strength. This magnetic field is applied to the location of the signal recording layer 101a of the magneto-optical disc 101 illuminated by the laser beam L.
Meanwhile, in this slider for the optical head 100, the through-hole 108 is bored through the slider member 102 along its thickness to a position of abutment against the thin-film coil 106, as described above, and the electrically conductive material is charged into this through-hole 108 to form the terminal 107 electrically connected to the thin-film coil 106.
However, since a variety of optical components, such as optical fiber 104 or the polarizing mirror 105, are built into the slider member 102, it becomes increasingly difficult to form the through-hole 108 in the slider member 102 for burying the above-mentioned terminal 107 as the slider for the optical head 100 becomes smaller in size.
Moreover, in forming the through-hole 108, the slider member 102 is subjected to punching using a diamond drill or an ultrasonic machining device. However, since this necessitates extremely fine working, defects termed chipping tend to be produced in the through-hole 108 formed, or the through-hole 108 sometimes cannot be formed to high precision at the intended location in the slider member 102.